1. Field of the Invention
This invention relates to a method and apparatus for filling liquid and gas cylinders, more particularly an apparatus that reduces the amount of process material gas wasted during the filling and disposal processes.
2. Prior Art
Presently, there are a variety of methods and apparatuses used for filling liquid and gas cylinders, including chlorine cylinders. Current methods and apparatuses used for filling chlorine cylinders use vacuum systems within the filling manifold to purge the manifold of chlorine for safe and effective operation. Vacuum systems, however, are expensive both from an equipment and a maintenance standpoint because special equipment is required to construct and maintain a vacuum system.
Presently, many chlorine cylinder handling systems comprise a source tank, a filling manifold, a purge gas source, a vacuum system to purge the manifold, and a neutralization tank. After each chlorine cylinder is filled, the filling manifold must be purged of chlorine. The purged chlorine flows into a holding tank where the purged chlorine is neutralized using caustic material. Units which process about 1000 pounds per day (ppd) of chlorine can use up to 18 ppd of caustic material within the holding tank. Caustic material is expensive, and after the caustic material has been depleted, the purged waste material, containing caustic and the neutralized chlorine, must be properly disposed. Thus, need exists for a chlorine tank filling apparatus that can decrease the costs associated with processing and disposal of the material within the holding tank and avoids using a vacuum system to purge the filling manifold.
During the filling process when toxic or hazardous chemicals are being transferred into smaller cylinders, chemical loss occurs when the cylinders are connected to and disconnected from the filling manifold. The chemical remaining in the lines connecting the filling manifold to the cylinders leaks to the environment. This chemical loss is a health risk to both the operator and to the surrounding areas.
The present invention has several advantages over the prior art. First, the operating pressures of the present invention range between 0 and 150 pounds per square inch gauge (psig). Thus, the added capital and maintenance expenses associated with the prior art vacuum systems for gas purging have been minimized. Second, the amount of chlorine lost during processing while using this invention has been drastically reduced to below 1 ppd. The disposal costs for the purged chlorine and the size required for the caustic holding tank have been reduced because less caustic material is used. Therefore, the overall costs of operating the apparatus decrease because the holding tank is emptied fewer times per year. Finally, the design of the present valve assembly reduces chemical loss at the cylinder connections by scaling both the cylinder and the filing manifold from the environment when the cylinders are connected to and disconnected from the manifold.
With the aforementioned considerations in mind, it is therefore an object of this invention to provide a safe and effective apparatus and method for filling tanks and cylinders.
It is a further object of this invention to provide an apparatus that avoids using a vacuum system for purging chlorine or other hazardous or toxic chemicals (xe2x80x9cprocess materialxe2x80x9d) within the filling apparatus.
It is a further object of this invention to provide an apparatus that reduces the amount of purged process material per filled cylinder.
It is a further object of this invention to provide an apparatus that reduces the amount of caustic material needed for effective operation of the apparatus.
It is a further object of this invention to provide an apparatus that includes a valve assembly connected between the manifold and the cylinders that substantially minimizes process material loss to the environment.
It is a further object of this invention to provide an apparatus that can fill multiple tanks without the necessity of purging or evacuating the system between tank fillings.
It is a further object of this invention to provide a valve assembly connected between the manifold and the cylinders that can reduce the health risks associated with operating a tank filling system where toxic or hazardous materials are being transferred through the apparatus.
These and other advantages and objects of this invention shall become apparent from the ensuing description of the invention.
An apparatus and method for filling chlorine cylinders is disclosed. The apparatus comprises a source of purge gas, a source of chlorine, and a manifold. The manifold comprises a purge gas port in fluid communication with the source of purge gas; a chlorine port in fluid communication with the source of chlorine; at least one cylinder port so that a cylinder to be filled with chlorine can attach to the manifold; and, a manifold outlet. The source of purge gas comprises a compressor having a purge gas inlet; a dryer connected to operatively connected to the compressor; a filter connected to said dryer; and, a purge gas outlet connectable to the purge gas port. The purge gas is selected from air, nitrogen, argon, or a combination thereof and is chemically inert to chlorine. The apparatus further comprises a holding tank connected to the manifold, which has a caustic neutralization agent therein, whereby said neutralization agent neutralizes the chlorine when the chlorine flows into the holding tank.
A valve assembly may be used in connection with the tank filling apparatus, or in connection with other apparatus or methods. The valve assembly comprises an inlet valve connectable to an outlet valve having a first end adapted to engage a receptacle for holding process material and configured to have an inlet port; a second end adapted to engage said second end of an outlet valve and configured to have an outlet port; a bore extending between the inlet and outlet ports; and, a first plug movably positioned in the bore, having an open and a closed position, and sealing the inlet port from the outlet port when in the closed position. The valve assembly further comprises an outlet valve having a first end adapted to en gage a source of process material and configured to have an inlet port; a second end adapted to engage the inlet valve and configured to have at n outlet port; a bore extending between the inlet and outlet ports; and, a second plug movably positioned in the bore, having an open and a closed position, and sealing the inlet port from the outlet port when in the closed position. The valve assembly also comprises a transfer tube having a first end configured to be insertable into the inlet valve bore and configured to have at least one port; a second end configured to be insertable into the outlet valve bore and configured to have at least one port; a bore extending through the transfer tube, allowing fluid communication bet we en the ports.
The valve assembly may further comprise inserts positionable within the bores of the inlet or outlet valves. The inserts have bores extending therethrough to allow fluid communication between the ends thereof which are configured with one or more ports. In such embodiments, the ends of the transfer tube are configured to be insertable into the b ores of the inserts.
The method for filling chlorine cylinders using the above described apparatus comprises at least the steps of: (a) pressurizing the manifold with purge gas; (b) depressurizing the manifold; (c) connecting a chlorine cylinder to the manifold; (d) displacing the purge gas within the manifold with chlorine; and (e) filling the chlorine cylinder with chlorine.